The Stones used
Knives and scrapers were made from hard fine-grained stones, such as chert, quartzite, chalcedony, and obsidian. Flint was occasionally used, but they are rare in New Zealand. Net-sinkers and pestles were made out of soft volcanic rocks, such as andesite and trachyte; while for adzes and meres any compact, hard, and tough rock was used. The commonest were igneous rocks, such as basalt, dolerite, and aphanite; but many of the rocks are metamorphic, such as hornstone and cherty-slate. Greenstone also comes under this head. Of it there are two varieties—(1) Nephrite, or pounamu, which is a silicate of magnesia and lime; and (2) bowenite, or tangiwai, which is a silicate of magnesia only, but contains a small quantity of water. Bowenite is softer than nephrite, and can be scratched with the point of a knife.